JP2023050700A - Gas production system and hydrocarbons production system - Google Patents

Abstract

To obtain a gas production system by which, when carrying out production of, for example, hydrocarbons, it is possible to produce gas suitable for the production.SOLUTION: A gas production system 120 includes at least an electrolytic reaction part 10 and a reverse water-gas shift reaction part 20, and produces gas containing hydrogen and carbon monoxide from water and carbon dioxide. The gas production system is configured so that moisture is supplied to the electrolytic reaction part 10, and an electrolytic reaction part outlet component containing at least hydrogen obtained by the electrolytic reaction part, and carbon dioxide are appropriately supplied to the reverse water-gas shift reaction part 20.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gas production system for producing a gas containing hydrogen and carbon monoxide from water and carbon dioxide, comprising at least an electrolytic reaction section and a reverse water-gas shift reaction section, and the electrolytic reaction section and the reverse water-gas shift reaction. The present invention relates to a hydrocarbon production system for producing hydrocarbons from at least water and carbon dioxide, comprising at least a hydrocarbon synthesis reaction part and a hydrocarbon synthesis reaction part.

A hydrocarbon production system is disclosed in Patent Document 1 or 2.
The system disclosed in US Pat. No. 5,900,003 is an electrolytic single cell (the electrolysis of the present invention) that produces either hydrogen or a raw material gas for synthesis ("synthesis gas", which stands for a mixture of hydrogen and carbon monoxide) from water vapor and carbon dioxide. A high temperature electrolyte (HTE) reactor (corresponding to the electrolysis reaction section of the present invention) equipped with a stack of cells (corresponding to the cell unit), and the synthesis gas obtained in this electrolysis single cell is converted to the desired by heterogeneous catalysis. Convert to combustible gas.
Therefore, in the technique disclosed in Patent Document 1, a hydrocarbon synthesis reaction section is provided downstream of the electrolytic reaction section to synthesize (manufacture) hydrocarbons using water and carbon dioxide as starting materials.

On the other hand, the technology disclosed in Patent Document 2 relates to a power-to-gas unit that produces useful gas (specifically methane) from electrical power, specifically the cathode of a stack of solid oxide (SOEC) basic electrolysis cells. discloses a technique involving a methanation catalyst material.
Also in the technique disclosed in Patent Document 2, the basic electrolysis cell serves as the electrolysis reaction section, and the methanation reaction catalyst material provided in the cathode constitutes the hydrocarbon synthesis reaction section.

In these prior arts, so-called "co-electrolysis" in which both water and carbon dioxide are electrolyzed is performed in the electrolysis reaction section. Heterogeneous catalysts are used for the synthesis of hydrocarbons (so-called methanation).

Japanese Patent Publication No. 2016-522166 JP 2019-112717 A

However, the inventors have found that there are the following problems with co-electrolysis and hydrocarbon synthesis in the electrolysis reaction section.
1. Problems of Co-Electrolysis Since the electrolysis voltage of water is around 1.23 V while the electrolysis voltage of carbon dioxide is around 1.33 V, the electrolysis reaction of carbon dioxide is less likely to occur than the electrolysis reaction of water. As a result, even if a co-electrolysis reaction is attempted, the electrolysis reaction of carbon dioxide is difficult to occur, and a sufficient concentration of carbon monoxide useful for synthesizing hydrocarbons cannot be ensured.

2. Problems in Hydrocarbon Synthesis For example, as a catalyst for synthesizing methane, which is an example of a hydrocarbon, it is known to use a heterogeneous catalyst in which nickel is supported on a metal oxide carrier. However, since the catalyst deteriorates due to the effects of carbon deposition, etc., there are problems in selecting the reaction conditions and usage conditions of the catalyst in order to use it stably for a long period of time, and there is room for improvement of the catalyst.
In addition, in the synthesis of hydrocarbons, depending on the concentration of carbon monoxide and carbon dioxide as a carbon source and the temperature in the production process, the so-called disproportionation reaction of carbon monoxide (expressed by the chemical formula 2CO ⇔ C + CO ₂₎ ) occurs, and carbon deposition is likely to occur.
Further, in synthesizing this kind of hydrocarbon, it is preferable to synthesize it at a relatively low temperature and pressure, but such a technique has not been established.

In view of this situation, the main object of the present invention is to obtain, for example, a gas production system that can produce a gas that can satisfactorily produce hydrocarbons, and a carbonization system that can satisfactorily produce hydrocarbons. It is to obtain a hydrogen production system.

The first characteristic configuration of the present invention is
A gas production system for producing a gas containing hydrogen and carbon monoxide from water and carbon dioxide, comprising at least an electrolytic reaction section and a reverse water gas shift reaction section,
Moisture is supplied to the electrolytic reaction section, and the electrolytic reaction section outlet component containing at least hydrogen and carbon dioxide obtained in the electrolytic reaction section are supplied to the reverse water gas shift reaction section.

This gas production system is provided with an electrolytic reaction section and a reverse water gas shift reaction section. In this configuration, the spatial positional relationship of each part is not limited, but it is sufficient that the gas decomposed in the electrolysis reaction section is transferred to the reverse water-gas shift reaction section to obtain the generated gas.

That is, in the electrolytic reaction section, at least water supplied to this section is decomposed to obtain hydrogen. The moisture to be supplied here may be water, steam, or a mixture thereof, in any form. In general, the reaction in the electrolytic reaction section is performed at a high temperature, so the water supplied to the reaction field of the electrolytic reaction section in such a form often reaches the reaction field in a gaseous state. On the other hand, to the reverse water gas shift reaction section, the electrolytic reaction section outlet component containing at least hydrogen obtained in the electrolytic reaction section and carbon dioxide are supplied. As a result, carbon monoxide is produced from carbon dioxide, and the gas (outlet component gas) obtained at this site contains at least carbon monoxide and can be a gas containing hydrogen. It is also possible to leave carbon dioxide in this gas. As a result, in addition to hydrogen obtained in the electrolysis reaction section, carbon monoxide produced in the reverse water gas shift reaction section can be used to efficiently obtain, for example, a gas useful for synthesizing hydrocarbons.

Therefore, for example, as described in the section on the subject above, even if co-electrolysis is attempted in the electrolytic reaction section and carbon monoxide is not produced well in the electrolytic reaction section, a reverse water gas shift reaction section is provided. Thus, a sufficient amount of carbon monoxide can be secured.

In addition, although the electrolytic reaction section is a reaction at a high temperature, the system efficiency can be enhanced by combining the reverse water gas shift reaction section, which is an endothermic reaction, with the electrolytic reaction section.

The second characteristic configuration of the present invention is
The present invention is provided with control means for controlling the amount of carbon dioxide supplied to the reverse water gas shift reaction section.

According to this characteristic configuration, the reaction in the reverse water-gas shift reaction section can be controlled in a suitable state by controlling the amount of carbon dioxide supplied to the reverse water-gas shift reaction section.

The third characteristic configuration of the present invention is
The point is that water and carbon dioxide are supplied to the electrolytic reaction part.

According to this characteristic configuration, hydrogen and a certain amount of carbon monoxide can be obtained by decomposing both water and carbon dioxide in the electrolysis reaction section. As previously indicated, co-electrolysis mainly contributes to the supply of hydrogen, but in the gas production system according to the present invention, by providing a reverse water gas shift reaction section downstream of the electrolysis reaction section, it becomes somewhat insufficient. Carbon monoxide can be supplemented in this reverse water gas shift reactor. Furthermore, when co-electrolysis is performed in the electrolytic reaction part, the gas flowing from the electrolytic reaction part contains water vapor, hydrogen, carbon dioxide and carbon monoxide, so that the reverse water gas shift reaction can be caused almost as it is. .

The fourth characteristic configuration of the present invention is
The present invention is provided with a first control means for controlling the amount of carbon dioxide supplied to the electrolysis reaction section.

By providing the first control means, even when co-electrolysis is performed in the electrolytic reaction section, the amount of carbon dioxide in the reaction section can be appropriately controlled, and the remainder is processed in the reverse water gas shift reaction section (reverse hydrogen gas shift process ) can be controlled to a suitable amount.

A fifth characteristic configuration of the present invention relates to a hydrocarbon production system,
The point is that at least a hydrocarbon synthesis reaction section is provided in the latter stage of the reverse water gas shift reaction section in the gas production system described so far.

According to this characteristic configuration, the gas containing at least hydrogen, carbon monoxide and carbon dioxide in a controlled state produced by the gas production system described so far is used to perform the hydrocarbon synthesis reaction Hydrocarbons can be synthesized in the part.

The sixth characteristic configuration of the present invention is
It is characterized in that a carbon dioxide supply section is provided between the reverse water gas shift reaction section and the hydrocarbon synthesis reaction section.

According to this characteristic configuration, the amount of carbon dioxide in the gas supplied from the gas production system to the hydrocarbon synthesis reaction section can be increased by supplying carbon dioxide from the carbon dioxide supply section.

The seventh characteristic configuration of the present invention is
The present invention is provided with a third control means for controlling the amount of carbon dioxide supplied from the carbon dioxide supply section.

According to this characteristic configuration, the amount of carbon dioxide to be introduced into the hydrocarbon synthesis reaction section can be appropriately controlled by the third control means.
By adopting this configuration, it is possible to satisfactorily control the problem of carbon deposition, which tends to occur in the process of synthesizing hydrocarbons, as described above.

An eighth characteristic configuration of the present invention relates to a hydrocarbon production system,
A hydrocarbon production system for producing hydrocarbons from at least water and carbon dioxide, comprising at least an electrolytic reaction section, a reverse water gas shift reaction section, and a hydrocarbon synthesis reaction section,
Moisture and carbon dioxide are supplied to the electrolysis reaction section, and a carbon dioxide supply section is provided between the reverse water gas shift reaction section and the hydrocarbon synthesis reaction section.

According to this characteristic configuration, even if at least hydrogen is generated in the electrolytic reaction part and co-decomposition is performed in this part, as described above, while making up for the shortage in the reverse water gas shift catalyst part, further, By supplying carbon dioxide from the carbon dioxide supply section, the synthesis reaction in the hydrocarbon synthesis reaction section can be brought into a favorable state.

The ninth characteristic configuration of the present invention is
The present invention is provided with control means for controlling the amount of carbon dioxide supplied from the carbon dioxide supply unit.

According to this characteristic configuration, the control means can appropriately control the amount of carbon dioxide to be introduced into the hydrocarbon synthesis reaction section.
By adopting this configuration, it is possible to satisfactorily control the problem of carbon deposition, which tends to occur in the process of synthesizing hydrocarbons, as described above.

A tenth characteristic configuration of the present invention is
The hydrocarbon synthesis reaction section is provided with a hydrocarbon synthesis catalyst containing at least ruthenium.

According to this characteristic configuration, a hydrocarbon synthesis reaction can be caused using a hydrocarbon synthesis catalyst containing at least ruthenium. As will be described later, ruthenium is highly active in synthesizing hydrocarbons (particularly methane synthesis) with respect to gases containing hydrogen and either or both of carbon monoxide and carbon dioxide. As can be seen from Table 12 according to the inventors' investigation, this catalyst can methanate both carbon monoxide and carbon dioxide to form hydrocarbons.
This synthesis reaction is a catalytic reaction, and the reaction temperature is preferably 225° C. or higher, more preferably 250° C. or higher, and even more preferably 275° C. or higher. In addition, if the reaction temperature becomes too high, for example, the equilibrium of the carbon monoxide methanation reaction, which is an exothermic reaction, will shift to the side of carbon monoxide production, making it impossible to obtain high-concentration methane. For example, the temperature is preferably 450° C. or lower, more preferably 400° C. or lower, and even more preferably 350° C. or lower.
Furthermore, in the hydrocarbon production system according to the present invention, the amount of carbon monoxide and carbon dioxide supplied to the hydrocarbon synthesis reaction section can be well controlled, so that the problem of carbon deposition described so far can be satisfactorily solved. can be reduced.

When manufacturing such a catalyst, it can be easily manufactured by an operation such as immersing a metal oxide support in a solution in which at least a ruthenium component is dissolved (so-called impregnation support). Therefore, the concentration of the ruthenium component with respect to the metal oxide support in the catalyst and the state of the ruthenium component supported on the metal oxide support can be well controlled, which is preferable.

Here, when obtaining this type of catalyst (hydrocarbon synthesis catalyst), it may be produced through a calcination step.

Moreover, when using, it is preferable to use it after performing a pre-reduction treatment.
At least part of ruthenium, which is a catalytically active component, of the catalyst obtained through the calcination step as described above is in the form of an oxide, and the catalyst may not exhibit its activity sufficiently. Therefore, pre-reduction treatment is carried out to reduce the catalytically active component in the oxidized state so that its activity can be exhibited sufficiently.

According to this characteristic configuration, hydrocarbons can be synthesized with high activity, as will be described later.

The eleventh characteristic configuration of the present invention is
The hydrocarbons synthesis reaction section is provided with a hydrocarbons synthesis catalyst containing at least ruthenium and vanadium.

As will be described later, a catalyst containing at least ruthenium and vanadium has high methanation ability and high ability to synthesize hydrocarbons having 2 or more carbon atoms. Therefore, the ethane concentration and propane concentration in the hydrocarbons produced by the hydrocarbons production system according to the present invention can be increased.

Diagram showing the configuration of a gas production system and a hydrocarbon production system Schematic diagram showing the configuration of the electrolytic reaction section Diagram showing the configuration of a system that integrates an electrolytic reaction section and a reverse water gas shift reaction section. Schematic diagram of an electrolytic cell unit equipped with an electrolytic reaction section and a reverse water gas shift reaction section Cross-sectional view of the electrolysis cell unit used in the comparative experiment with the gas supply channel on the electrode layer side as the reverse water-gas shift reaction section Configuration diagram of a system provided with a heat exchanger between the electrolytic reaction section and the reverse water gas shift reaction section Schematic diagram of the system that directs _CO2 to the reverse water gas shift reactor Schematic diagram of the system that directs _CO2 to the electrolytic reaction section and the reverse water gas shift reaction section Configuration diagram of the system that introduces _CO2 to the electrolysis reaction section and the hydrocarbon synthesis reaction section A diagram showing another configuration of a hydrocarbon production system equipped with a hydrogen separation section A diagram showing yet another configuration of the system provided with a water separation section before the hydrocarbon synthesis reaction section. Explanatory drawing showing the preparation state of the catalyst Explanatory drawing showing the coating/calcination state of the catalyst and pre-reduction treatment Schematic diagram of an electrolytic cell unit equipped with an electrolytic reaction section, a reverse water gas shift reaction section, and a hydrocarbon synthesis reaction section

An embodiment of the present invention will be described based on the drawings.
FIG. 1 shows one configuration of a hydrocarbon production system 100 including a gas production system 120 proposed by the present inventors.
As shown in the figure, the gas production system 120 is configured with an electrolytic reaction unit 10 and a first catalytic reaction unit 20 as main functional units, and the hydrocarbon production system 100 includes these functional units 10 and 20 in addition to , and a second catalytic reaction section 30 . Therefore, the second catalytic reaction section 30 receives the gas produced by the gas production system 120 from the gas production system 120 and produces hydrocarbons. In the following description, the hydrocarbon production system 100 will be mainly described.

The hydrocarbon production system 100 includes an electrolytic reaction section 10, a first catalytic reaction section 20, a second catalytic reaction section 30, a heavy hydrocarbon separation section 35 (illustrated as a CnHm separation section), a water separation section 40 (H ₂ O separation unit in the drawing) and a carbon dioxide separation unit 50 (CO ₂ separation unit in the drawing) in this order.

The electrolytic reaction part 10 is a part for electrolyzing at least part of the inflowing gas, the first catalytic reaction part 20 is a reverse water-gas shift reaction part for performing a reverse water-gas shift reaction on at least part of the inflowing gas, The second catalytic reaction section 30 is configured to function as a hydrocarbon synthesis reaction section for synthesizing at least part of the inflowing gas into hydrocarbons. Here, the synthesized hydrocarbons are mainly CH ₄ (hydrocarbon with 1 carbon atom), but also include lower saturated hydrocarbons with 2 to 4 carbon atoms. Furthermore, as will be described later, by appropriately selecting the catalyst used in the second catalytic reaction section 30, heavy hydrocarbons having a higher number of carbon atoms than the lower saturated hydrocarbons, hydrocarbons not saturated, oxygen-containing hydrocarbons, etc. can also be synthesized.

The heavy hydrocarbon separation section 35, the water separation section 40, and the carbon dioxide separation section 50 are sites for removing at least a portion of predetermined components (CnHm, H ₂ O, and CO ₂ in order of description) from the gas flowing therein. be. Components removed and recovered by the water separation unit 40 and the carbon dioxide separation unit 50 are returned to predetermined parts of the system via a water return path 41 and a carbon dioxide return path 51 as shown in FIG. used. Corresponding to both return paths 41, 51 are indicated H ₂ O and CO ₂ returning via respectively.
As a result, this hydrocarbon production system 100 is established as a carbon closed system that does not substantially release CO ₂ to the outside of the system.

In the figure, the gas flowing into each part is shown before each part, and the gas discharged from the part is shown afterward.

In the electrolysis reaction section 10, H ₂ O and CO ₂ as starting materials are introduced and electrolyzed inside to decompose H ₂ O into H ₂ and O ₂ and part of CO ₂ is decomposed into CO and _O2 and released.

The reaction is described as follows.
2H ₂ O→2H ₂ +O ₂ (formula 1)
2CO ₂ →2CO+O ₂ (formula 2)
These formulas 1 and 2 are also shown in the box showing the electrolytic reaction section 10 in FIG.

In the first catalytic reaction unit 20 (reverse water gas shift reaction unit), H ₂ and CO ₂ are introduced, a reverse water gas shift reaction occurs therein, CO ₂ becomes CO, and H ₂ becomes H ₂ O and released. be.

Although the reaction is described as an equilibrium reaction below, the reverse water gas shift reaction is a reaction in which the reaction described in Equation 3 below proceeds to the right (CO ₂ and H ₂ react to form CO and H ₂ O reaction).
CO ₂ + H ₂ ⇔ CO + H ₂ O (equation 3)
This formula 3 is also shown in the box showing the first catalytic reaction section 20 (reverse water gas shift reaction section) in FIG. In this box, the reverse water gas shift catalyst cat1 used for the reaction is also shown schematically.

At least H ₂ and CO are introduced into the second catalytic reaction section 30 (hydrocarbon synthesis reaction section), and hydrocarbons are synthesized by catalytic reaction. For example, the reaction in which _CH4 is synthesized from CO and _H2 is described as an equilibrium reaction below, whereas the reaction in which _CH4 is synthesized from CO and _H2 is represented by the reaction described in Equation 4 below. (a reaction in which CO and H ₂ react to produce CH ₄ and H ₂ O).
CO + _3H2 ⇔ _CH4 + _H2O (formula 4)
This formula 4 is also shown in the box showing the second catalytic reaction section 30 (hydrocarbons synthesis reaction section) in FIG. In this box, the hydrocarbon synthesis catalyst cat2 used for the reaction is also shown schematically.
Furthermore, the equilibrium reaction of (equation 3) also occurs at this site. Therefore, a reaction in which _CH4 is synthesized from CO2 and _H2 , which is the sum of (Equation ₃ ) and (Equation 4) (reaction in which (Equation 5) proceeds to the right), may also occur.
_CO2 + _4H2 <-> _CH4 + _2H2O (equation 5)
In addition, depending on the type of catalyst used in the second catalytic reaction unit 30 _, FT (Fischer-Tropsch) synthesis reaction or the like can proceed. etc., paraffins, olefinic hydrocarbons, and various other hydrocarbons can be synthesized.

As will be described later, the inventors have shown an example of a catalyst using ruthenium as its catalytically active component as the hydrocarbon synthesis catalyst cat2 placed in the second catalytic reaction section 30. Heavy hydrocarbons are also synthesized with catalysts containing iron, cobalt, etc., and such heavy hydrocarbons can be condensed and separated from the carrier gas as the temperature drops. Therefore, in the heavy hydrocarbon separation section 35 described above, the hydrocarbon components thus separated are separated.

The H ₂ O produced in the water separation section 40 is separated and returned to the upstream side of the electrolytic reaction section 10 via a water return path 41 (water recycling line).

The CO ₂ generated in the carbon dioxide separation unit 50 is separated and passed through a carbon dioxide return path 51 (carbon dioxide recycling line) to a predetermined site of the system (specifically, the inlet of the electrolytic reaction unit 10, the reverse water gas shift reaction unit). 20, the inlet of the hydrocarbon synthesis reaction section 30).

In the system (gas production system 120, hydrocarbon production system 100) according to the present invention, the predetermined parts 10, 20, 30 are provided with a carbon dioxide source 70 (described as a CO ₂ source) or a carbon dioxide return path 51 (carbon dioxide By appropriately controlling the carbon dioxide supplied from the recycle line), the composition of the gas supplied to each part 10, 20, 30 is adjusted (controlled) to an appropriate state.

On the other hand, this system (gas production system 120, hydrocarbon production system 100) requires the supply of H ₂ O, which is supplied to the electrolytic reaction section 10 as moisture (water, steam, or a mixture thereof). can supply.

As shown in the figure, the system 120, 100 according to the present invention is provided with control means M for controlling the amount of carbon dioxide supplied to each of the parts 10, 20, 30. FIG. In this example, as the control means M, a first control means M1, a second control means M2, and a third control means M3 are provided.

The first control means M1 controls the amount of carbon dioxide supplied to the electrolysis reaction section 10 .
The second control means M2 controls the amount of carbon dioxide supplied between the electrolytic reaction section 10 and the reverse water gas shift reaction section 20.
The third control means M3 controls the amount of carbon dioxide supplied between the reverse water gas shift reaction section 20 and the hydrocarbon compound synthesis reaction section 30. In the present invention, a portion that supplies carbon dioxide between the reverse water gas shift reaction section 20 and the hydrocarbon synthesis reaction section 30 is called a "carbon dioxide supply section."

Here, each of the control means M1, M2 and M3 can be composed mainly of, for example, a common flow control valve (not shown) and a control mechanism (not shown) for controlling the valve. Also, the amount of carbon dioxide supplied by each of the control means M1, M2, M3 includes a state of no supply to a finite predetermined amount.

It is possible to supply carbon dioxide to the corresponding units 10, 20, and 30 by all the control means M1, M2, and M3. , not only when co-decomposition is performed to perform electrolysis of H ₂ O and CO ₂ , but also when electrolysis of only H ₂ O is performed without supplying CO ₂ to the electrolytic reaction unit 10, the second By activating the control means M2, it is possible to appropriately perform carbon monoxide synthesis in the reverse water gas shift reaction section 20.

As a result, in this gas production system 120, the composition of gas containing at least hydrogen and carbon monoxide produced by this system 120 can be appropriately controlled and supplied to the outside. Furthermore, in the hydrocarbon production system 100, hydrocarbons are finally synthesized and can be supplied to the outside.

The outlines of the gas production system 120 and the hydrocarbon production system 100 have been described above, and the configuration and role of each part will be described below.
[Electrolytic reaction part]
As described above, the electrolysis reaction section 10 consumes the power supplied according to the formulas 1 and 2 to decompose the incoming H ₂ O and CO ₂ .

FIG. 2 schematically shows the cross-sectional configuration of the electrolytic reaction section 10. As shown in FIG.
The figure shows an electrolysis cell unit U that is laminated in multiple layers to form an electrolysis stack (not shown). The electrolysis cell unit U includes an electrolysis cell 1. The electrode layer 2 is provided on one surface, and the counter electrode layer 3 is provided on the other surface. The electrode layer 2 serves as a cathode in the electrolytic cell 1, and the counter electrode layer 3 serves as an anode. Incidentally, this electrolytic cell unit U is supported by a metal support 4 . Here, the case of using a solid oxide electrolysis cell as the electrolysis cell 1 is exemplified.

The electrolyte layer 1a can be formed in the form of a thin film having a thickness of 10 μm or less. Its constituent materials include YSZ (yttria-stabilized zirconia), SSZ (scandia-stabilized zirconia), GDC (gadolinium-doped ceria), YDC (yttrium-doped ceria), SDC (samarium-doped ceria), and LSGM. (Strontium/magnesium added lanthanum gallate) and the like can be used. In particular, zirconia-based ceramics are preferably used.

This electrolyte layer 1a is formed by a low-temperature firing method (for example, a wet method using a firing process in a low-temperature range without firing in a high-temperature range exceeding 1100° C.) or a spray coating method (a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, etc.). Position method, powder jet deposition method, particle jet deposition method, cold spray method, etc.), PVD method (sputtering method, pulse laser deposition method, etc.), CVD method, etc. are preferable. By these film formation processes that can be used in a low temperature range, the electrolyte layer 1a that is dense, airtight, and has high gas barrier properties can be obtained without using sintering in a high temperature range exceeding 1100° C., for example. Therefore, damage to the metal support 4 can be suppressed, and element mutual diffusion between the metal support 4 and the electrode layer 2 can be suppressed, and an electrolytic cell unit U excellent in performance and durability can be realized. In particular, it is preferable to use a low-temperature baking method, a spray coating method, or the like, since a low-cost device can be realized. Furthermore, it is more preferable to use the spray coating method, since the electrolyte layer 1a that is dense, airtight, and has high gas barrier properties can be easily obtained in a low temperature range.

Further, the electrolyte layer 1a is densely structured in order to block gas leakage and exhibit high ionic conductivity. The density of the electrolyte layer 1a is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. When the electrolyte layer 1a is a uniform layer, it preferably has a denseness of 95% or more, more preferably 98% or more. Further, when the electrolyte layer 1a is composed of a plurality of layers, it is preferable that at least a part of them contain a layer (dense electrolyte layer) having a density of 98% or more, such as 99%. It is more preferable to include the above layer (dense electrolyte layer). When such a dense electrolyte layer is included in a part of the electrolyte layer 1a, even if the electrolyte layer 1a is composed of a plurality of layers, the dense electrolyte layer 1a with high airtightness and gas barrier properties can be obtained. This is because it is easy to form

The electrode layer 2 can be provided in the state of a thin layer on the front surface of the metal support 4 in a region larger than the region where the holes 4a are provided. In the case of a thin layer, the thickness can be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. With such a thickness, it is possible to secure sufficient electrode performance while reducing costs by reducing the amount of expensive electrode layer material used. The entire area in which the hole (through hole) 4 a is provided is covered with the electrode layer 2 . That is, the hole 4a is formed inside the region of the metal support 4 where the electrode layer 2 is formed. In other words, all holes 4a are provided facing electrode layer 2 .

Composite materials such as NiO--GDC, Ni--GDC, NiO--YSZ, Ni--YSZ, CuO-- _CeO.sub.2 and Cu-- _CeO.sub.2 can be used as the constituent material of the electrode layer 2, for example. In these examples, GDC, YSZ, _CeO2 can be referred to as the composite aggregate. The electrode layer 2 can be formed by a low-temperature firing method (for example, a wet method using a firing process in a low-temperature range without firing in a high-temperature range higher than 1100 ° C.) or a spray coating method (a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, powder jet deposition method, particle jet deposition method, cold spray method, etc.), PVD method (sputtering method, pulse laser deposition method, etc.), CVD method, or the like. These processes, which can be used in the low temperature range, yield good electrode layers 2 without using high temperature firing, for example higher than 1100°C. Therefore, the metal support 4 is not damaged, element mutual diffusion between the metal support 4 and the electrode layer 2 can be suppressed, and an electrochemical device excellent in durability can be realized, which is preferable. Furthermore, it is more preferable to use the low-temperature firing method because the handling of the raw material is facilitated.

The counter electrode layer 3 can be formed in the state of a thin layer on the surface of the electrolyte layer 1 a opposite to the electrode layer 2 . In the case of a thin layer, the thickness can be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. With such a thickness, it is possible to secure sufficient electrode performance while reducing costs by reducing the amount of the expensive counter electrode layer material used. As a material for the counter electrode layer 3, for example, composite oxides such as LSCF and LSM, ceria-based oxides, and mixtures thereof can be used. In particular, counter electrode layer 3 preferably contains a perovskite oxide containing two or more elements selected from the group consisting of La, Sr, Sm, Mn, Co and Fe.
The electrolyte layer 1a, the electrode layer 2 and the counter electrode layer 3 are formed as thin films as will be described later, and the inventor calls this a thin layer formation.

As described above, the electrolysis cell unit U is of the metal support type, and includes the metal support 4 as a support for the electrode layer 2. The metal support 4 is sandwiched between the electrode layers 2 and the U A supply path forming member 5 for forming a letter-shaped electrode layer side gas supply path 5a is provided. Further, a large number of holes 4a are provided in the metal support 4 so as to penetrate the front and back surfaces thereof. Gases (H ₂ O and CO ₂ ) supplied through the electrode layer-side gas supply passage 5a are subject to electrolysis and are supplied to the electrode layer 2 through numerous holes 4a. Furthermore, the generated gas (H ₂ , CO) is discharged from this hole 4a.

On the other hand, on the counter electrode layer 3 side, a supply path forming member 6 for forming a counter electrode layer side gas supply path 6a is provided. As shown in the figure, the supply channel forming member 6 is provided with many grooves on the side of the counter electrode layer 3 so as to supply a carrier gas g2 (for example, air) to the counter electrode layer side gas supply channel 6a. It is configured.

The metal support 4 supports the electrode layer 2, the electrolyte layer 1a, and the counter electrode layer 3 to maintain the strength of the electrolytic cell 1 and the electrolytic cell unit U as a whole. In this example, a plate-like metal support 4 is used as the metal support, but other shapes such as box-like, cylindrical, etc. are also possible.
The metal support 4 may have sufficient strength to form the electrolytic cell unit U as a support, for example, about 0.1 mm to 2 mm, preferably about 0.1 mm to 1 mm, more preferably about 0.1 mm to 1 mm. A thickness of about 0.1 mm to 0.5 mm can be used. Although the support is made of metal in this embodiment, it can also be made of ceramics, for example.

The metal support 4 has, for example, a plurality of holes 4a penetrating through the front side surface and the back side surface of the metal plate. For example, the holes 4a can be provided in the metal support 4 by mechanical, chemical or optical drilling or the like. The holes 4a have the function of allowing gas to permeate from the back surface of the metal support 4 to the front surface. The holes 4a may be inclined in the direction of gas advection (the direction of the front and back of the paper in FIG. 2).

By using a ferritic stainless steel material (an example of an Fe—Cr alloy) as the base material of the metal support 4, YSZ (yttria stabilized zirconia) and GDC (yttria stabilized zirconia) used as materials for the electrode layer 2 and the electrolyte layer 1a Gadolinium-doped ceria, also called CGO), etc., can have a similar thermal expansion coefficient. Therefore, the electrolytic cell unit U is less likely to be damaged even when the temperature cycle of low temperature and high temperature is repeated. Therefore, it is possible to realize an electrolytic cell unit U excellent in long-term durability, which is preferable.

The supply path forming members 5 and 6 of the electrolytic cell unit U can be made of the same material as the metal support 4, and can have substantially the same thickness.

The metal support 4 and the supply path forming members 5 and 6 are electrically conductive, but by being airtight, they function as separators for separating the supply paths 5a and 6a.

In the electrolysis cell unit U having the above configuration, in electrolysis operation, DC power is supplied from a power supply unit (indicated by a battery in FIG. 2) between a pair of electrode layers 2 and 3 provided with an electrolyte layer 1a interposed therebetween. supply. In this embodiment, as shown in the figure, the electrode layer 2 side is negative and the counter electrode layer 3 side is positive. Depending on the configuration of the electrolytic cell unit U, the electrode layer 2 side may be positive and the counter electrode layer 3 side may be negative.
Then, H ₂ O and CO ₂ , which are gases to be electrolyzed, are supplied to the electrode layer 2 from the electrolytic raw material supply unit (the upstream portion of the electrolytic reaction unit 10 in FIG. 1), and the carrier gas is supplied to the counter electrode layer side. By supplying g2, the reactions shown in the formulas 1 and 2 can be caused in the electrolytic cell 1, and the decomposed gas can be taken out. Here, as for the supply of H ₂ O, either one of water and steam may be used, or both of them may be used. We refer to this form of H ₂ O as moisture. Therefore, in the present invention, at least an electrolysis cell unit U, an electrolysis raw material supply section for supplying water and/or steam and carbon dioxide to the electrolysis cell unit U, and an electric power supply section for supplying electric power are provided. An electrolytic cell device is constructed.

Gases (H ₂ O, CO ₂ ) supplied in the electrolytic reaction and gases (H ₂ O, H ₂ , CO, O ₂ , CO ₂ ) released in the electrolytic reaction are shown above and below the electrolytic cell unit U in FIG. However, this is for the purpose of facilitating understanding. Actually, the electrode layer side gas supply channel 5a and the counter electrode layer side gas supply channel 6a are formed extending in the front and back directions of the paper surface of FIG. _For example _, in _FIG . H ₂ , CO, O ₂ , CO ₂ ) can be recovered from the back side of the paper (see FIG. 4 described later). A carrier gas g2 such as air can also be flowed into the electrolytic cell unit U in order to smoothly discharge O ₂ generated in the electrolytic reaction.

When H ₂ O and CO ₂ are supplied to the electrolytic reaction unit 10 _and electrolyzed, H ₂ O has a lower electrolysis voltage than CO ₂ and is easily electrolyzed. When CO ₂ is supplied to the electrolytic reaction section 10 for electrolytic reaction, the H ₂ concentration tends to be higher than the CO concentration at the outlet of the electrolytic reaction section 10 , and unreacted CO ₂ tends to remain.

[First catalytic reaction section (reverse water gas shift reaction section)]
As previously indicated, the first catalytic reaction section 20 (reverse water gas shift reaction section) causes a reverse water gas shift reaction to convert _CO2 to CO using the supplied _H2 , Let ₂ be _H2O . That is, in the electrolytic reaction section 10 which supplies H ₂ O and CO ₂ and electrolyzes them, the CO ₂ remaining without being decomposed is converted into CO.

The reaction here is as shown in Formula 3, but this reaction is an endothermic reaction and is an equilibrium reaction depending on the reaction temperature conditions. As a result, as described above, it is preferable that the catalyst is capable of causing the reaction represented by Formula 3 at a temperature as high as possible (for example, 600° C. to 800° C.).

In describing catalysts in this specification, a component having catalytic activity is sometimes referred to as a "catalytically active component", and a carrier that supports the catalytically active component is sometimes referred to as a "support".
The inventors have investigated various combinations of catalytically active components and supports, as described below, and have found certain combinations to be suitable.
This type of catalyst is produced by carrying out an impregnation supporting step in which a support (metal oxide support) is immersed in a solution containing a catalytically active component (active metal), taken out, dried and heat-treated to obtain A support-supported catalyst (impregnated support) in which catalytically active components are distributed can be easily obtained. This heat treatment is firing treatment. Preparation and use of the catalyst are described with reference to FIGS.

The preparation methods described here are the same for various combinations of catalytically active components and supports, with only the starting materials being different. FIG. 12 shows both examples of the reverse water gas shift catalyst cat1 and the hydrocarbon synthesis catalyst cat2 according to the present invention. In the figure, the catalytically active component of the reverse water gas shift catalyst cat1 is denoted by ca1, and its carrier is denoted by cb1. On the other hand, regarding the hydrocarbon synthesis catalyst cat2, its catalytic active component is ca2 and its carrier is cb2.

As shown in FIG. 12, in catalyst preparation, an aqueous solution of a compound containing a metal component (which is a metal catalyst) serving as catalytically active components ca1 and ca2 is obtained, and carriers cb1 and cb2 are added to the aqueous solution and stirred. , After performing the impregnation and supporting step (a) of impregnating, evaporating to dryness, drying, and then performing the drying/pulverizing/forming step (b) of pulverizing and molding, etc., and the obtained molded body is placed in the air. By executing the firing step (c) of firing, the target objects (cat1, cat2) can be obtained. This form of catalyst is therefore also called an impregnated supported catalyst.

In this case, as shown in the example of the reverse water gas shift catalyst cat1 in FIG. 13, the catalyst can be applied to the site to be used and then calcined. FIG. 13(a) shows a coating/baking process in which the reverse water gas shift catalyst cat1 is applied to the metal support 4 having the holes 4a to form the coating layer 20a and then baked. FIG. 13(b) shows a pre-reduction treatment step in which H ₂ is flowed to pre-reduce before the reverse water gas shift catalyst cat1 is used.

When the calcination treatment is performed in the air, the supported catalytically active components ca1 and ca2 are partially or wholly oxidized. Before the catalyst is used, a so-called pre-reduction treatment can be carried out to reduce the catalytically active components in the oxidized state and to sufficiently increase their activity. FIG. 13(b) shows a state in which a reducing gas (typically H ₂ ) is passed through the surface of the catalyst to perform pre-reduction treatment.

(Catalyst used)
As the reverse water gas shift catalyst cat1 used in the first catalytic reaction section 20, the inventors have selected a catalyst that satisfies the following requirements.

A catalyst comprising at least one or both of nickel and iron as a catalytically active component ca1 supported on a carrier cb1 mainly composed of a ceria-based metal oxide or a zirconia-based metal oxide. Here, since the strength of the catalyst cat1 can be increased, the ratio of the carrier cb1 to the entire catalyst is preferably 55% by weight or more, more preferably 60% by weight or more, and further preferably 65% by weight or more. preferable. In addition, the upper limit of this ratio can be, for example, 99.5% by weight, but if it exceeds this, the catalytically active component ca1 cannot be sufficiently supported, and it may become difficult to obtain the effect of the reverse water gas shift catalyst cat1. is.

Furthermore, the ceria-based metal oxide may be ceria doped with at least one of gadolinium, samarium, and yttrium.
Zirconia stabilized with at least one of yttria and scandia can also be used as the zirconia-based metal oxide.

In addition, since the reverse water gas shift reaction can proceed well, the amount of the catalytically active component ca1 supported is preferably 0.5% by weight or more, more preferably 1% by weight or more, and 5% by weight or more. is more preferable. Moreover, even if the amount of the catalytically active component ca1 supported is excessively increased, it becomes difficult to support the catalytically active component ca1 in a highly dispersed manner, making it difficult to obtain a significant improvement in catalytic activity and increasing the cost of the catalyst. The amount of the catalytically active component ca1 supported is preferably 35% by weight or less, more preferably 30% by weight or less, and even more preferably 25% by weight or less.

Furthermore, it is also preferable to add either one or both of nickel and iron to the catalytically active component ca1 and carry copper as a further catalytically active component ca1. In this configuration, the supported amount of copper is equal to or less than the supported amount of the catalytically active component ca1 for either one or both of nickel and iron as the main active component ca1.

Test results of examples in which the catalytically active component ca1 and the carrier cb1 of the reverse water gas shift catalyst cat1 used in the first catalytic reaction section 20 are variously changed will be described below.
As the catalytically active component ca1, Ni and Fe were examined and compared with Pt (platinum).
For the carrier cb1, ZrO ₂ (zirconia), YSZ (yttria-stabilized zirconia), GDC (gadolinium-doped ceria), CeO ₂ (ceria) were used as examples, and Al ₂ O ₃ (alumina) was also investigated.

In the following description, Test Examples 1 and 2 will be introduced, but the difference between the two tests is that in the calcination of the reverse water gas shift catalyst cat1, the calcination temperature of Test Example 1 was 450 ° C., and that of Test Example 2 was The point is that the temperature is set to the high temperature side of 600°C to 1000°C.

(Test example 1)
Test results of Examples (1 to 19) in which various carriers were used as the catalyst used in the first catalytic reaction section 20 will be described.
As a catalytically active component, Ni and Fe were examined and Pt (platinum) was compared.
Examples of the support include ZrO ₂ (zirconia), YSZ (yttria-stabilized zirconia), GDC (gadolinium-doped ceria), and CeO ₂ (ceria), and Al ₂ O ₃ (alumina) was also investigated.

(Catalyst preparation)
In the preparation of the reverse water gas shift catalyst cat1, water-soluble nickel compounds (nickel nitrate, nickel chloride, nickel sulfate, nickel ammonium sulfate, nickel acetate, nickel oxalate, nickel citrate, etc.), One or both of water-soluble iron compounds (iron nitrate, iron chloride, iron sulfate, ammonium iron sulfate, iron acetate, iron oxalate, iron citrate, etc.) are quantified and dissolved to obtain an aqueous solution. In addition, when supporting copper as a further catalytically active component ca1, a water-soluble copper compound (copper nitrate, copper chloride, copper sulfate, copper ammonium sulfate, copper acetate, copper oxalate, copper citrate, etc.) is similarly added. Quantify and obtain a dissolved aqueous solution. A predetermined amount of carrier powder (ceria, zirconia, GDC, YSZ, Al ₂ O ₃ ) is added to the aqueous solution, stirred and impregnated, evaporated to dryness, dried, then pulverized, molded, and fired in air. do. This impregnation is the "impregnation support step" referred to in the present invention, and the resulting product is the "impregnation support".
The catalysts of the following examples were prepared using nickel nitrate hexahydrate, iron nitrate nonahydrate, and copper nitrate trihydrate. Also, a catalyst using Pt was prepared using tetraammineplatinum hydroxide.

In the preparation of the above catalyst, the temperatures for evaporation to dryness, drying, and calcination can be carried out in a temperature range generally used. , 80°C, and 450°C.

Table 1 shows Examples 1 to 19 of the reverse water gas shift catalyst cat1 in the present invention.
The horizontal axis represents the type of carrier cb1, the amount of metal supported as a catalytically active component (% by weight; expressed as wt.% in the table), the amount of CO adsorption (ml/g), and the BET surface area (m ² /g). there is
As for the amount of CO adsorption, the amount of CO adsorption was measured after the catalyst was subjected to pre-reduction treatment at 350° C. in a hydrogen atmosphere for one hour.

(Catalytic activity test)
In the catalytic activity test, a mixed gas of 50% H ₂ -50% CO ₂ (mixed gas containing H ₂ and CO ₂ at a volume ratio of 1:1) was used as the reaction gas, and GHSV (Gas Hourly Space Velocity) was used. under the condition of 10000/h, while changing the reaction temperature from 600°C to 800°C in increments of 50°C.
Before conducting the catalytic activity test, the catalyst was pre-reduced at 600° C. while hydrogen gas was passed through the catalyst layer.
As test results, Table 2 shows the CO concentration (%) and CH4 concentration (%) at the outlet of the reaction section, along with the CO ₂ conversion rate (%).

The CO ₂ conversion rate (%) was calculated according to the following formula based on the results of gas analysis at the outlet of the catalyst layer.
[CH ₄ concentration] + [CO concentration] / ([CH ₄ concentration] + [CO concentration] + [CO ₂ concentration])

As shown earlier, the reverse water-gas shift catalyst cat1 used in the first catalytic reaction section 20 (reverse water-gas shift reaction section) has a CO ₂ conversion rate (% ) is desirable.

(Test example 2)
The test results of Examples (20 to 29) of Test Example 2 will be described below. Even in this example,
Ni and Fe were investigated as catalytically active components, and the addition of Cu was also investigated.
Examples of the carrier include CeO ₂ (ceria) and ZrO ₂ (zirconia), and Al ₂ O ₃ (alumina) was also investigated.

(Catalyst preparation)
The reverse water gas shift catalyst cat1 used in Test Example 2 was prepared in the same manner as in Test Example 1, except that the calcination temperature was changed to 600°C, 800°C, and 1000°C.

Table 3 shows the respective catalysts of Examples (20-29) prepared.

(Catalytic activity test)
In the catalytic activity test, a mixed gas containing H ₂ and CO ₂ at a ratio of 1:1 (volume ratio) was used as the reaction gas, and the reaction temperature was changed from 600°C to 800°C in increments of 50°C under the conditions of GHSV of 10000/h. I went while changing it.
Before conducting the catalytic activity test, the catalyst was pre-reduced at 600° C. while hydrogen gas was passed through the catalyst layer.
As the test results, Table 4 shows the CO concentration (%) and _CH4 concentration (%) at the outlet of the reaction section, along with the _CO2 conversion rate (%).

For reference, Table 4 shows the equilibrium values (calculated values) of CO ₂ conversion under the experimental conditions.

Iron/Zirconia Catalyst and Iron/Alumina Catalyst Regarding the iron/zirconia catalyst, the test results when the firing temperature was 450° C., 600° C., 800° C., and 1000° C. are shown in Examples 8, 22, and 26, respectively. It is shown in Example 29. On the other hand, with regard to the iron/alumina catalyst, the test results obtained when the calcination temperature was 450° C., 600° C. and 800° C. are shown in Examples 14, 23 and 27, respectively. As can be seen from these results, the iron/zirconia catalyst is more active than the iron/alumina catalyst in the reverse water gas shift reaction, although the amount of metal supported is slightly different. In addition, iron/zirconia catalysts have extremely high catalytic activity not only when the calcination temperature is 450°C, but also when the calcination temperature is increased to 600°C, 800°C, and 1000°C. CO ₂ conversion reaches near the equilibrium value even when .

Nickel-Ceria Catalyst Test results for calcination temperatures of 450° C., 600° C., 800° C. and 1000° C. are shown in Examples 4, 20, 24 and 28, respectively. As can be seen from these results, the nickel-ceria catalyst has extremely high catalytic activity not only when the calcination temperature is 450°C, but also when the calcination temperature is increased to 600°C, 800°C, and 1000°C. , and the CO ₂ conversion reaches the vicinity of the equilibrium value at any calcination temperature.

Nickel-Alumina Catalyst Test results are shown in Example 7 for a calcination temperature of 450°C. The results showed that the nickel-alumina catalyst resulted in lower _CO2 conversion than the nickel-ceria catalyst previously described.

Nickel/Copper/Ceria Catalyst The test results for the sintering temperatures of 450° C., 600° C. and 800° C. are shown in Examples 6, 21 and 25, respectively. From these results, it can be seen that with the nickel-copper-ceria catalyst, the _CO2 conversion rate tends to decrease slightly when the calcination temperature increases to 600°C or 800°C. Superior to iron/alumina catalysts. In addition, with the nickel-copper-ceria catalyst with a calcination temperature of 450°C, the CO ₂ conversion reaches the vicinity of the equilibrium value.

Usefulness as a reverse water gas shift catalyst As shown above, iron/zirconia catalysts and nickel/ceria catalysts exhibit extremely high reverse water resistance even when the sintering temperature is varied from 450°C to 1000°C. Since it exhibits gas shift catalytic activity, it is useful because it facilitates ensuring high performance and durability even when used in combination with a solid oxide type electrolysis cell used in a high temperature range of, for example, around 600°C to 800°C.

From the above results, as shown above, as the reverse water gas shift catalyst cat1 used in the first catalytic reaction section 20, the carrier cb1 mainly composed of ceria-based metal oxide or zirconia-based metal oxide, A catalyst configured by supporting at least one or both of nickel and iron as the catalytically active component ca1 can be used.

Furthermore, the ceria-based metal oxide as the carrier cb1 may be ceria doped with at least one of gadolinium, samarium, and yttrium.

Also, the zirconia-based metal oxide as the carrier cb1 can be zirconia stabilized with at least one of yttria and scandia.

Furthermore, it is also preferable to add either one or both of nickel and iron to the catalytically active component ca1 and carry copper as a further catalytically active component ca1.

By using the reverse water-gas shift catalyst cat1 in the first catalytic reaction section 20 (reverse water-gas shift reaction section), it has high activity but is equivalent to a very expensive Pt catalyst at around 600 to 1000 ° C. The reverse water _- gas shift reaction can be carried out at a CO2 conversion rate (%) above.
In addition, since the test of this example is a test conducted under very high GHSV conditions of 10000/h, the conditions under which the GHSV is lower than 10000/h, that is, the amount of catalyst used with respect to the amount of gas to be treated By increasing , it is also possible to perform the reverse water-gas shift reaction at higher _CO2 conversions (%).

[Combination of electrolytic reaction section and reverse water gas shift reaction section]
In the description so far, according to the system configuration shown in FIG. 1, the electrolytic reaction section 10 and the reverse water gas shift reaction section 20 are separately provided in the order described along the gas advection direction.
Depending on the reaction conditions, the reaction in the electrolytic reaction section 10 may be an exothermic reaction, and the reaction in the reverse water gas shift reaction section 20 may be an endothermic reaction. Therefore, by integrating these two reaction sections 10 and 20, the thermal efficiency of the system can be improved. FIG. 3 shows the configuration in which these two reaction sections 10 and 20 are combined and integrated as described above, and both sections are enclosed to indicate that they are integrated. Therefore, this part corresponds to the gas production system 120 of the present invention. Also, the reactions when they are integrated in the same box are shown. Basically, Equations 1, 2, and 3 shown above are performed. When the electrolytic reaction section 10 and the reverse water-gas shift reaction section 20 are combined and integrated, if they are surrounded by a heat-insulating member, heat transfer between the electrolytic reaction section 10 and the reverse water-gas shift reaction section 20 will occur. can be performed efficiently. Further, in order to transfer the heat generated in the electrolytic reaction section 10 to the reverse water-gas shift reaction section 20, the electrolytic reaction section 10 and the reverse water-gas shift reaction section 20 may be connected using a heat transfer member. When adopting this configuration, the control means M provided in the hydrocarbon production system 100 may include a first control means M1 and a third control means M3.

[Electrolytic cell unit provided with both an electrolytic reaction part and a reverse water gas shift reaction part]
Based on the above concept, it is preferable to provide the reverse water gas shift reaction section 20 in the electrolytic cell unit U serving as the electrolytic reaction section 10 . This is because when a solid oxide type electrolytic cell that operates at around 600 to 800° C. is used as the electrolytic cell 1, the reverse water gas shift catalyst cat 1 of the present application, in which high activity is obtained at around 600 to 800° C., is used in the electrolytic reaction section 10. and the reverse water gas shift reaction section 20 can be used in the same temperature range.
Also in this case, it is sufficient that the gas that has passed through the electrolytic reaction section 10 is led to the reverse water-gas shift reaction section 20 to generate the reverse water-gas shift reaction.

FIG. 4 shows an electrolytic cell unit U provided with such a reverse water gas shift reaction section 20 . FIG. 4 is a diagram showing the electrolysis cell unit U shown in cross section in FIG. 2, including the advection direction of the gas.

As shown in the figure, the sections of the electrolytic cell unit U are basically the same.
That is, this electrolysis cell unit U also includes an electrolysis cell 1 in which an electrode layer 2 and a counter electrode layer 3 are formed with an electrolyte layer 1a interposed therebetween, a metal support 4 that functions as a support for the electrolysis cell 1 and also serves as a separator, a supply It is composed of path forming members 5 and 6, and is configured to form an electrode layer side gas supply path 5a and a counter electrode layer side gas supply path 6a. More specifically, as can be seen from the figure, when the metal support 4 is viewed in the direction of gas advection, the hole 4a is provided at the site corresponding to the electrolytic cell 1, but the hole 4a is provided on the downstream side of the electrode layer 2. is not perforated. Therefore, the metal support 4 contains the gas supplied to the electrode layer 2 and released from the electrode layer 2, and the gas supplied to the counter electrode layer 3 and released from the counter electrode layer 3. is a separator that effectively separates

However, in this example, the inner surface of the electrode layer side gas supply channel 5a (the inner surface of the supply channel forming member 5 on the supply channel side, the surface of the metal support 4 opposite to the surface on which the electrode layer 2 is formed, and the plurality of holes 4a surface) is coated with the above-described reverse water gas shift catalyst cat1. This coating layer 20a is indicated by a thick solid line.
Further, the electrode-layer-side gas supply passage 5a extends beyond the electrolytic reaction section 10, and the coating layer 20a is also provided on this extension side.

As a result, the electrode layer side gas supply passage 5a of the electrolysis cell unit U serves as a discharge passage for discharging at least H ₂ generated in the electrode layer 2, and the electrolytic reaction section 10 and the reverse water gas shift reaction section 20 are integrated. It becomes the structure with which the electrolytic cell unit U was equipped.

In this configuration, the _metal support 4 functions as a separator for separating H2 generated in the electrode layer 2 and _O2 generated in the counter electrode layer 3. and a gas shift reaction section 20 .
By stacking the electrolytic cell units U configured in this manner in the left-right direction in FIGS. omitted) can be formed. Naturally, the useful gas produced can be obtained over multiple layers.

Under the concept of combining the electrolytic reaction section 10 and the reverse water-gas shift reaction section 20 (using the electrode layer side gas supply passage 5a of the electrolytic reaction section 10 as the reverse water-gas shift reaction section 20), the inventors An experiment was conducted with the granular reverse water-gas shift catalyst cat1 housed in the gas supply path 5a.
FIG. 5 shows a cross section of the electrolytic cell unit U subjected to this experiment.

A specific description will be given below with reference to FIG. The figure shows a cross-sectional view of the electrolytic cell unit U. As shown in FIG.
Here, as the electrolytic cell 1, a metal-supported solid oxide type electrolytic cell was used. As the metal support 4, a metal substrate was prepared by providing a plurality of through holes (to become the holes 4a) in a metal plate of ferritic stainless steel having a thickness of 0.3 mm by laser processing. An electrode layer 2 and an intermediate layer 2a were laminated in this order on the metal substrate, and an electrolyte layer 1a was laminated on the intermediate layer 2a of the metal substrate so as to cover the intermediate layer 2a. Further, the reaction prevention layer 7 and the counter electrode layer 3 were laminated in order on the electrolyte layer 1a to prepare the electrolytic cell 1. As shown in FIG. A mixture of NiO powder and GDC powder is used as the material for forming the electrode layer 2, GDC powder is used as the material for forming the intermediate layer 2a, and 8YSZ (8 mol% yttria-stable Zirconia) powder was used, GDC powder was used as the material for forming the reaction prevention layer 7 , and a mixture of GDC powder and LSCF powder was used as the material for forming the counter electrode layer 3 . The thicknesses of the electrode layer 2, the intermediate layer 2a, the electrolyte layer 1a, the reaction prevention layer 7, and the counter electrode layer 3 are about 25 μm, about 10 μm, about 5 μm, about 5 μm, and about 20 μm, respectively. rice field. By providing an intermediate layer 2a between the electrode layer 2 and the electrolyte layer 1a, or by providing a reaction prevention layer 7 between the electrolyte layer 1a and the counter electrode layer 3, the performance and durability of the electrolytic cell 1 can be improved. can be improved. In addition, the intermediate layer 2a and the reaction prevention layer 7 may be formed by a low-temperature firing method (for example, a wet method using a firing process in a low-temperature range without firing in a high-temperature range higher than 1100° C.) or a spray coating method (thermal spraying or aerosol deposition). position method, aerosol gas deposition method, powder jet deposition method, particle jet deposition method, cold spray method, etc.), PVD method (sputtering method, pulse laser deposition method, etc.), CVD method, etc. is preferred. By these processes that can be used in a low temperature range, a good intermediate layer 2a and reaction prevention layer 7 can be obtained without using sintering in a high temperature range higher than 1100° C., for example. Therefore, it is possible to realize an electrolytic cell 1 excellent in performance and durability without damaging the metal support 4, which is preferable. Furthermore, it is more preferable to use the low-temperature firing method because the handling of the raw material is facilitated.

In the electrolytic cell unit U obtained as described above, a reverse water gas shift catalyst formed in granules is provided in the electrode layer side gas supply channel 5a (which also serves as a discharge channel for the gas electrolyzed in the electrolytic reaction section 10). A study was made on the performance improvement when accommodating cat1.

Results when the reverse water gas shift catalyst cat1 was not accommodated Electrolytic reaction was performed while supplying gas containing H ₂ O and CO ₂ to the electrolytic cell unit U, and the ratio of H ₂ to CO in the outlet gas of the electrolytic cell unit U was measured using a gas chromatograph. The results are shown in Table 5 below. The results of this experiment are described as Comparative Examples A1 and A2.

Results when the reverse water gas shift catalyst cat1 was accommodated As the reverse water gas shift catalyst cat1, a granular catalyst obtained by supporting about 10% Ni on the 8YSZ carrier similar to that of Example 2 was accommodated and placed in the electrolytic cell unit U. An electrolytic reaction was performed while supplying a gas containing H ₂ O and CO ₂ , and the ratio of H ₂ and CO in the outlet gas of the electrolytic cell unit U was measured using a gas chromatograph. The results are shown in Table 6. The result of this experiment was described as Example A1.

According to the above comparative experiments, the electrolytic cell 1 is formed in a thin layer on the metal support 4, and the reverse water-gas shift reaction section 20, which generates CO using CO ₂ and the H ₂ by the reverse water-gas shift reaction, is electrolyzed. In the electrolysis cell unit U provided in the electrode layer side gas supply channel 5a, which serves as an exhaust channel for the discharged gas, the composition ratio of CO to H ₂ generated by electrolysis was able to be increased.

In comparison between the electrolysis cell unit U that does not house the reverse water gas shift catalyst cat1 in the electrode layer side gas supply channel 5a (which serves as a discharge channel for the electrolyzed gas) and the electrolysis cell unit U that houses it, hydrogen/ The carbon monoxide ([H ₂ /CO]) ratio is about 10 or more to about 5, and the combination of the reaction in the electrolytic reaction section 10 and the reaction in the reverse water gas shift reaction section 20 is advantageous for various hydrocarbon synthesis. It is preferable because it is possible to secure the amount of In addition, since it is possible to increase the thermal efficiency of the hydrocarbon production system 100 by adopting the CO methanation reaction rather than the CO ₂ methanation reaction, the reaction in the electrolytic reaction unit 10 and the reverse water gas shift reaction unit 20 Since the amount of CO can be ensured by combining the reactions of the above, it is preferable. This is because methanating 1 mol of CO produces 2 mol of H ₂ O, whereas _methanating 1 mol of CO only produces 1 mol of H ₂ O. This is because the hydrocarbon production system 100 that employs the methanation reaction of CO can suppress the loss of latent heat and sensible heat of 1 mol of H ₂ O as the entire system.
In addition, the ratio of H ₂ O and CO ₂ introduced into the electrolytic reaction section 10, the reaction conditions of the electrolytic reaction section 10 (electrolysis voltage, reaction temperature, etc.), the reaction conditions of the reverse water gas shift reaction section 20 (the amount of catalyst used, GHSV, reaction temperature, etc.), the hydrogen/carbon monoxide ([H ₂ /CO]) ratio at the outlet of the reverse water gas shift reaction unit 20 can be adjusted to the second catalytic reaction unit 30 (hydrocarbons (for example, H ₂ /CO=3, which is the equivalent ratio for the methanation reaction of CO).

[A heat exchanger is installed between the electrolytic reaction part and the reverse water gas shift reaction part]
In the description so far, the example in which the electrolytic reaction section 10 and the first catalytic reaction section (reverse water gas shift reaction section) 20 are integrated has been mainly described. A heat exchanger 11 may be provided between the parts 10 and 20 to adopt a configuration in which heat can be exchanged between the two parts. This configuration is shown in FIG. 6 corresponding to FIG. Hollow double lines indicate heat transfer between the two sites. With this configuration, the temperature of each part 10, 20 can be appropriately controlled.
The control of the supply of carbon dioxide to the electrolytic reaction section 10, the reverse water gas shift reaction section 20, and the hydrocarbon synthesis reaction section 30 is the same as before.

[Second catalytic reaction section (hydrocarbon synthesis reaction section)]
In this second catalytic reaction section 30 (hydrocarbon synthesis reaction section), at least H ₂ and CO are flowed in, and hydrocarbons (methane and various hydrocarbons having 2 or more carbon atoms) and the like are generated by catalytic reaction. .

(Example of hydrocarbon synthesis catalyst)
As an activity test of the catalyst (hydrocarbons synthesis catalyst cat2) used in the second catalytic reaction section 30, the inventors conducted evaluation test 1, evaluation test 2, evaluation test 3, and evaluation test 4 shown below.

As an example of the hydrocarbon synthesis catalyst cat2, catalysts were prepared by variously changing the carrier and catalytically active components. As the catalytically active component ca2, Ru, Ru with addition of Mo, V, Fe, Co, etc., and Ni were examined. ZrO ₂ , Al ₂ O ₃ , SiO ₂ , MgO and TiO ₂ were investigated as the carrier cb2.

(Catalyst preparation)
The preparation of the hydrocarbons synthesis catalyst cat2 is also the adopted method explained in FIGS.
That is, according to the composition of the target catalyst, a water-soluble ruthenium compound (ruthenium nitrate, ruthenium chloride, ruthenium sulfate, ruthenium ammonium sulfate, ruthenium acetate, ruthenium oxalate, ruthenium citrate, etc.) is quantitatively dissolved to obtain an aqueous solution. Further, when molybdenum, vanadium, iron, and cobalt are supported as additional catalytically active components, these water-soluble metal compounds are similarly quantified to obtain an aqueous solution in which they are dissolved. Using the aqueous solution, a predetermined amount of carrier particles (ZrO ₂ , Al ₂ O ₃ , SiO ₂ , MgO, TiO ₂ ) is impregnated with a catalytically active component, for example, and carried thereon. A hydrocarbon synthesis catalyst cat2 can be obtained by applying a treatment step.
The catalysts used in the following examples are an aqueous solution of ruthenium chloride, an aqueous solution of ammonium molybdate, an aqueous solution of vanadyl oxalate, an aqueous solution of iron nitrate, and an aqueous solution of cobalt nitrate. It was prepared using a sequential loading method (a two-stage loading method in which a catalytically active component other than ruthenium is first loaded onto a carrier and then ruthenium is loaded).

(Evaluation test 1)
In evaluation test 1, a mixed gas containing 12.4% CO, 24.8% _CO2 , 37.2% _H2 , 12.4% _H2O , and the balance _N2 was used as the reaction gas. , GHSV was set to 4000/h (WET basis), and the activity test of the hydrocarbon synthesis catalyst cat2 was conducted at a reaction temperature between 275°C and 360°C. In this case, the reaction gas is a co-electrolytic reaction of water and carbon dioxide in the electrolysis reaction unit 10 under the condition that the electrolysis reaction rate of carbon dioxide is low, and the reverse water gas shift reaction unit 20 installed in the subsequent stage. A model in which a mixed gas of CO, CO ₂ , H ₂ , and H ₂ O after the reverse water gas shift reaction of carbon is performed is introduced into the hydrocarbons synthesis reaction section 30 to carry out a hydrocarbon synthesis reaction. An example.

The following two indicators were used to organize the test results.

1. Assumed hydrocarbon conversion rate for CO ₂ removal = [carbon number of hydrocarbons in outlet gas]/[carbon number in outlet gas - carbon number in outlet CO ₂ ]
This index is an index that indicates the conversion rate to hydrocarbons when CO ₂ is removed from the outlet gas of the hydrocarbon synthesis reaction section 30 obtained by the catalytic reaction, and it is preferable that this index is high.

2. C1-C4 calorific value (MJ/Nm ³ )=Σ(Nn×HN)/ΣNn
Nn [mol]: the number of moles of Cn hydrocarbons in the catalytic reaction part gas (n = 1 to 4)
HN [MJ/m ³ (N)]: calorific value of Cn hydrocarbon in catalytic reaction part gas [H1 = 39.8, H2 = 69.7, H3 = 99.1, H4 = 128.5]
This index is an index that indicates the amount of C1 to C4 components contained in the outlet gas of the hydrocarbon synthesis reaction unit 30 obtained by the catalytic reaction, and when this value exceeds 39.8, ethane other than methane It can be confirmed that hydrocarbons such as , propane, and butane are produced.

Regarding the evaluation test 1, Tables 7 and 8 below show examples B1 to B3 of the catalyst for synthesizing hydrocarbons cat2 of the present invention.

As shown in Tables 7 and 8, from a mixed gas of CO, CO ₂ , H ₂ and H ₂ O, as hydrocarbon synthesis catalyst cat 2, a catalyst in which ruthenium is supported on an alumina carrier, a catalyst in which ruthenium is supported on an alumina carrier, and molybdenum in addition to ruthenium Alternatively, it was confirmed that hydrocarbons can be synthesized using a vanadium-supported catalyst.
From the above results, it was confirmed that the hydrocarbon production system 100 can produce a high calorie gas with a C1-C4 calorific value of 39 MJ/Nm ³ or more.

(Evaluation test 2)
In evaluation test 2, a mixed gas containing 0.45% CO, 18.0% _CO2 , 71.55% _H2 , and 10.0% _H2O was used as the reaction gas, and the GHSV was 5000/ h (DRY base), the activity test of the catalyst for synthesizing hydrocarbons cat2 was conducted at a reaction temperature between about 230°C and about 330°C. The reaction gas in this case is a mixed gas obtained when the co-electrolytic reaction of water and carbon dioxide is carried out in the electrolysis reaction section 10 under conditions where the electrolysis reaction rate of carbon dioxide is low. This is an example that assumes a model in which a hydrocarbon synthesis reaction is carried out by introducing into

The following two indicators were used to organize the test results.

1 Hydrocarbon conversion rate = [carbon number of hydrocarbon in exit gas] / [carbon number in exit gas]
This index is an index that indicates the ratio of the number of carbons converted to hydrocarbons without being converted to CO ₂ in the total carbon that flows in, and it is preferable that this index is high.

2 CO ₂ removal assumed hydrocarbon conversion rate = [carbon number of hydrocarbon in outlet gas] / [carbon number in outlet gas - carbon number in outlet CO ₂ ]
This index is an index showing the conversion rate to hydrocarbons when CO ₂ is removed from the outlet gas of the hydrocarbon synthesis reaction section obtained by the catalytic reaction, and this index is also preferably high.

For Evaluation Test 2, the catalysts used (Examples B4 to B16) are shown in Table 9, and the test results are shown in Table 10.

(Evaluation test 3)
In evaluation test 3, a mixed gas (H ₂ /CO = 3) containing H ₂ and CO at a volume ratio of 3:1 was used as the reaction gas, the GHSV was 2000 / h, and the temperature was 235 ° C. to about 330 ° C. An activity test of the catalyst for synthesizing hydrocarbons cat2 was carried out at a reaction temperature between In this activity test, catalysts (Examples B17 and B18) in which iron or cobalt was supported in addition to ruthenium on a titania carrier were used. The reaction gas in this case is a mixed gas obtained by adding carbon monoxide to hydrogen obtained by electrolyzing water in the electrolytic reaction unit 10, or a gas obtained by performing a co-electrolysis reaction of water and carbon dioxide. A model is assumed in which a mixed gas of hydrogen and carbon monoxide obtained by separating water or carbon dioxide as necessary is introduced into the hydrocarbon synthesis reaction section 30 to carry out a hydrocarbon synthesis reaction. It is an example of a thing.

Table 11 shows the results of Evaluation Test 3.

As shown in Table 11, it was confirmed that hydrocarbons can be synthesized from a mixed gas containing H ₂ and CO using a catalyst in which ruthenium and iron or cobalt are supported on a titania carrier as the hydrocarbon synthesis catalyst cat2. did it.

It was confirmed that the above-described hydrocarbon production system 100 could produce a high calorie gas with a C1-C4 calorific value of 39 MJ/Nm ³ or more.

From the above results, as shown above, a catalyst in which at least ruthenium is supported as a catalytically active component ca2 on a metal oxide carrier cb2 can be used in the second catalytic reaction section 30 (hydrocarbons synthesis reaction section). . Furthermore, it is preferable to support at least one of molybdenum, vanadium, iron and cobalt as the catalytically active component ca2.

The hydrocarbon synthesis catalyst cat2 is preferably a catalyst in which at least ruthenium is supported on the metal oxide support cb2, and the amount of ruthenium supported is preferably 0.1% by weight or more and 5% by weight or less, and the metal It has been found that the oxide support cb2 preferably supports at least one of molybdenum, vanadium, iron and cobalt as a catalytically active component ca2 in addition to ruthenium.

At least one of molybdenum, vanadium, iron and cobalt may be supported in an amount of 0.2% by weight or more and 6% by weight or less.

In addition, among such hydrocarbon synthesis catalyst cat2, the carbon monoxide adsorption amount of the catalyst with high activity was 0.4 ml/g or more.

[Heavy hydrocarbon separation part]
By cooling the gas that reaches the heavy hydrocarbon separation unit 35, the heavy hydrocarbons contained in the gas released from the hydrocarbons synthesis reaction unit 30 are condensed, and the heavy hydrocarbons are extracted to the outside. be able to. For example, the 2 wt. % Ru/2wt. A mixed gas (H ₂ /CO=3) containing H ₂ and CO at a ratio of 3:1 (volume ratio) was introduced into the hydrocarbon synthesis reaction section 30 using a %Fe/TiO ₂ catalyst, and heated to 275°C. When the reaction was carried out at the heavy hydrocarbon separation section 35, linear higher aliphatic hydrocarbons having an average chain length of 26 carbon atoms could be extracted. 35, a linear higher aliphatic hydrocarbon having an average chain length of 18 carbon atoms could be obtained.
From the above results, it was confirmed that the hydrocarbon production system 100 can produce a high calorie gas with a C1-C4 calorific value of 39 MJ/Nm ³ or more.

[Water separator]
The water separator 40 is provided with a condenser, which adjusts the inflowing H ₂ O-containing gas to a predetermined temperature and pressure, condenses it, and extracts water to the outside.

[Carbon dioxide separator]
For example, PSA is arranged in this part 50, and CO 2 is separated from the inflowing gas containing CO ₂ by being adsorbed on the adsorbent under a predetermined temperature and pressure, and the separated _{CO 2 is} Good separation of CO ₂ by desorption from the adsorbent. The separated CO ₂ can be returned to the front of the electrolytic reaction section 10 via the carbon dioxide return path 51 and reused.
Note that the carbon dioxide separator and the water separator can be made into the same separator by using PSA or the like.

As described above, the system according to the present invention (the gas production system 120 and the hydrocarbon production system 100) can produce useful gases. , in the hydrocarbon synthesis reaction unit 30, it is preferable that carbon monoxide and carbon dioxide are converted to methane based on the above formula 4 or formula 5. A carbon ratio of 3:1 to 4:1 is preferred. In other words, if 100 mol of water is put into the system, it is ideally preferable to put about 25 to 33 mol of carbon dioxide into the system, but about 25 to 33 mol of carbon dioxide is For example, using the first control means M1, the second control means M2, and the third control means M3, carbon dioxide is supplied to each of the parts 10, 20, and 30 at a ratio of about 1:1:1. can be controlled to Further, control may be performed so that carbon dioxide is supplied to each of the portions 10, 20, and 30 at a ratio of about 0:1:2 to 0:2:1. Alternatively, control may be performed so that carbon dioxide is supplied to each of the portions 10, 20, and 30 at a ratio of about 1:0:2 to 2:0:1. In particular, the control of the supply of carbon dioxide to these systems is particularly important from the viewpoint of suppressing carbon deposition due to the disproportionation reaction of carbon monoxide (expressed by the chemical formula 2CO ⇔ C + CO ₂ ) and carbon dioxide in the electrolytic cell. In view of the electrolysis rate of , the first supply control means M1, the second control means M2, and the third control means M3 may be used for appropriate distribution and supply of carbon dioxide.

[Another embodiment]
(1) In the above embodiment, an example was shown in which both H ₂ O and CO ₂ were supplied to the electrolytic reaction section 10 and subjected to an electrolytic reaction. A system in which only ₂ O is supplied and subjected to an electrolysis reaction may be employed. In this case, the carbon consumed in the hydrocarbon synthesis is introduced into the reverse water gas shift reaction section 20 as carbon dioxide. In this case, since conversion of CO ₂ to CO is mainly performed in the reverse water-gas shift reaction section 20 , the return destination of CO ₂ may be before the reverse water-gas shift reaction section 20 . As the control means M, the second control means M2 described so far may be provided.

Of course, as shown in FIG. 8, the return destination of carbon dioxide may be the electrolytic reaction section 10 and the reverse water gas shift reaction section 20, and a configuration in which no return path to the hydrocarbon compound synthesis reaction section 30 is provided can also be adopted. As the control means M, the first control means M1 and the second control means M2 which have been explained so far may be provided.
On the other hand, as shown in FIG. 9, the return destination of carbon dioxide may be the electrolysis reaction section 10 and the hydrocarbon synthesis reaction section 30, and a configuration in which a return path to the reverse water gas shift reaction section 20 is not provided may also be adopted. As the control means M, the first control means M1 and the third control means M3 described above may be provided.

(2) In the above embodiment, H ₂ in the gas obtained from the hydrocarbon _synthesis reaction section 30 was not particularly described, but a hydrogen separation section ( A _H2 separator 60 may be provided to separate _H2 and use it separately. This configuration is shown in FIG. In this example, the H ₂ separated in the hydrogen separation section 60 may be returned before the reverse water-gas shift reaction section 20 and used for the reverse water-gas shift reaction.

(3) In the above embodiment, the water separation section 40 is provided downstream of the hydrocarbons synthesis reaction section 30, but as shown in FIG. You may provide the water separation part 40 between. The main function of this water separator 40 is to facilitate the hydrocarbon synthesis reaction.

(4) In the above embodiment, an example of using a solid oxide electrolysis cell as the electrolysis cell 1 in the electrolysis reaction section 10 was shown, but as the electrolysis cell 1, an alkaline electrolysis cell, a polymer membrane electrolysis cell, or the like is used. You can use it.

(5) In the above embodiment, the configuration in which the electrolytic reaction section 10 and the first catalytic reaction section 20 are integrated is shown. It is also possible to configure A configuration example in this case is shown in FIG. Incidentally, in this figure, 30a indicates the coating layer of the hydrocarbon synthesis catalyst cat2.
Also in this configuration, each of these reactors 10, 20, 30 can be constructed on a metal support 4, which serves as a separator between the hydrocarbons produced and the oxygen. It has become.

(6) In the above embodiment, an example of synthesizing hydrocarbons such as methane in the hydrocarbon synthesis reaction section 30 was shown, but how to select a hydrocarbon synthesis catalyst to be used in the hydrocarbon synthesis reaction section 30 Depending on the situation, it is also possible to synthesize chemical raw materials from hydrogen and carbon monoxide introduced into the hydrocarbon synthesis reaction section 30 .

1 electrolytic cell 1a electrolyte layer 2 electrode layer 3 counter electrode layer 4 metal support (support/separator)
4a hole 5 supply path forming member (separator)
6 supply path forming member (separator)
10 Electrolytic reaction section 20 First catalytic reaction section (reverse water gas shift reaction section)
20a Coating layer 30 Second catalytic reaction section (hydrocarbon synthesis reaction section)
40 water separation section 50 carbon dioxide separation section 60 hydrogen separation section M control means M1 first control means M2 second control means M3 third control means U electrolytic cell unit cat1 reverse water gas shift catalyst ca1 catalytically active component (active metal)
cb1 carrier (metal oxide carrier)
cat2 hydrocarbon synthesis catalyst ca2 catalytically active component (active metal)
cb2 support (metal oxide support)

Claims (11)

A gas production system for producing a gas containing hydrogen and carbon monoxide from water and carbon dioxide, comprising at least an electrolytic reaction section and a reverse water gas shift reaction section,
A gas production system in which water is supplied to the electrolytic reaction section, and the electrolytic reaction section outlet component containing at least hydrogen and carbon dioxide obtained in the electrolytic reaction section are supplied to the reverse water gas shift reaction section. 2. The gas production system according to claim 1, further comprising control means for controlling the amount of carbon dioxide supplied to said reverse water gas shift reaction section. 2. The gas production system according to claim 1, wherein water and carbon dioxide are supplied to said electrolytic reaction section. 4. The gas production system according to claim 3, further comprising first control means for controlling the amount of carbon dioxide supplied to said electrolytic reaction section. 5. A hydrocarbons production system comprising at least a hydrocarbons synthesis reaction section downstream of said reverse water gas shift reaction section in the gas production system according to any one of claims 1 to 4. 6. The hydrocarbon production system according to claim 5, further comprising a carbon dioxide supply section between said reverse water gas shift reaction section and said hydrocarbon synthesis reaction section. 7. The hydrocarbon production system according to claim 6, further comprising third control means for controlling the amount of carbon dioxide supplied from said carbon dioxide supply unit. A hydrocarbon production system for producing hydrocarbons from at least water and carbon dioxide, comprising at least an electrolytic reaction section, a reverse water gas shift reaction section, and a hydrocarbon synthesis reaction section,
A hydrocarbon production system, wherein water and carbon dioxide are supplied to the electrolysis reaction section, and a carbon dioxide supply section is provided between the reverse water gas shift reaction section and the hydrocarbon synthesis reaction section. 9. The hydrocarbon production system according to claim 8, further comprising control means for controlling the amount of carbon dioxide supplied from said carbon dioxide supply unit. 10. The hydrocarbons production system according to any one of claims 5 to 9, wherein said hydrocarbons synthesis reaction section comprises a hydrocarbons synthesis catalyst containing at least ruthenium. The hydrocarbons production system according to any one of claims 5 to 10, wherein the hydrocarbons synthesis reaction section comprises a hydrocarbons synthesis catalyst containing at least ruthenium and vanadium.

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